The incidence of 2 rare types of childhood cancers decreased after the United States began to require manufacturers to add folic acid to cereal and other grain products, according to a study published today in the journal Pediatrics. But the overall rate of childhood cancers held steady.
The processes that contribute to some childhood cancers may trace back to the womb. Some scientists hypothesize that folic acid deficiency may contribute to the development of such malignancies. Various mechanisms that might explain this phenomenon have been proposed. One possibility is that folate deficiency may lead to less production of the nucleic acid thymine, resulting in substitution of uracil and ultimately hindering DNA repair. Alternatively, some have suggested that folate deficiency leads to decreased methylation of DNA, disrupting the expression oncogenes or leading to general genetic instability.
To probe the links between childhood cancer and folic acid supplementation, the authors of the study compared the incidence of childhood cancers among 3790 children who were in utero before the implementation in 1998 of folic acid fortification of certain US foods and 3299 who were in utero after supplementation became required. They found that overall, the incidence of childhood cancers was unchanged, but the rates of Wilms tumor, primitive neuroectodermal tumors, and ependymomas were lower after fortification.
The authors caution that this epidemiologic study can’t prove a causal relationship between folic acid supplementation and reduced rates of cancer; other factors, such as changes in classification of tumors or other societal-level changes intended to reduce cancer rates, may have contributed to the reduced rates of Wilms tumor, primitive neuroectodermal tumors, and ependymomas. And it’s also not clear why rates of some other tumors went up during the same period.
Concerns have also been raised about the potential downside of folic acid supplementation. Some countries, for example, have not adopted folic acid fortification because of concerns that such fortification might actually increase rates of some cancers. The authors suggest that comparing childhood cancer rates in countries that do fortify their foods with folate with countries that don’t may help clarify the relationship between childhood cancer and folic acid supplementation.